Hydraulic downhole oil recovery system

ABSTRACT

An improved hydraulic downhole oil recovery system that incorporates an above ground unit and a submersible, reciprocating downhole pump unit. Water-based fluid, rather than hydraulic fluid, is responsible for actuating the reciprocating downhole pump unit. The water-based fluid is transferred through the system using coil, coil tubing. The system further relies upon coil exterior production tubing to provide exceptional advantage in deviated oil wells.

CITATION TO PARENT APPLICATION(S)

This is a continuation-in-part with respect to U.S. patent application Ser. No. 10/884,376, filed on Jul. 2, 2204, from which priority is claimed pursuant to 35 U.S.C. 120.

BACKGROUND OF THE INVENTION

1. Field of The Invention

Applicant's invention generally relates to an improved hydraulic downhole oil recovery system. More specifically, Applicant's invention relates to an oil recovery system that employs coil tubing, in both its production tubing and fluid transfer tubing, and water-based fluid, rather than hydraulic fluid, to offer its user tremendous advantages in view of systems known in the art.

2. Background Information

Conventional oil recovery systems are hampered by limitations on both the depth and volume of oil that can be recovered. The present invention does away with these presently accepted limitations. In fact, known oil recovery systems can generally recover 400 barrels of oil per day, at a depth of 1000 feet, using full-sized standard surface pumps. However, embodiments of Applicant's invention will be able to recover 700 barrels per day, using a fraction of the energy consumed by conventional systems. Particular embodiments of the present invention allow certain embodiments of the system to be maintained on solar energy, which is not feasible with known downhole oil recovery systems.

Conventional oil recovery systems are relatively short-lived and require a high level of maintenance in view of the present device. Current systems rely on large, cumbersome parts that are prone to leaking and causing wear and tear of standard production tubing. However, Applicant's invention provides a much smaller surface unit, with less moving parts, and incorporates coil tubing. As such, the maintenance and the risk of leaks are reduced.

A large portion of the problems associated with known oil recovery systems come from the secured-production tubing configuration of those systems. Specifically, reciprocation of the sucker rod within the production tube causes wear and tear of the tubing. As a result, leaks often originate within the tubing at the secured reciprocation location. This leads to both inefficiency and environmental contamination. Such problems are exaggerated in the common case of deviated oil wells. As will be further discussed, Applicant's invention eliminates these common problems through the novel use of coil production tubing.

Common oil recovery systems also present significant problems at the surface. Surface pumps are loud, cumbersome, visually offensive, dangerous, and environmentally unfriendly. As such, restrictions are placed on both where and when these systems can be used. Prohibitive zoning restrictions are often based on the way the pumps look, how they sound, and the inconvenience they cause to people in their proximity. Further, it is widely known in the art that conventional surface pumps are prone to leaking both oil and hazardous fumes. As such, environmental concerns are very high and periodic maintenance is required, all the while cost of operation increases while efficiency decreases.

Surface pumps are also dangerous; each year, there are several injuries and deaths that result from the operation of such pumps. These casualties often involve children who make their way to the pumps, drawn by curiosity, only to get caught in the moving parts.

Applicant's invention provides a refreshing solution to the problems mention above and avoids the worst characteristics associated with known surface pumps. The present invention uses only a fraction of the energy required for standard surface pumps. As such, the present invention is much smaller and quieter, is easily housed and insulated, and greatly reduces the likelihood of leaks and need for maintenance. Further, the present invention eliminates the dangers associated with surface pumps as there are no large, cumbersome moving parts.

There is a narrow range of hydraulically operated oil recovery systems known in the art. Yet, of these known systems, none are believed to be operative in reality, and at best are not able to match the advantages provided by Applicant's invention. For instance, Schulte (U.S. Pat. No. 5,494,102) discloses a downhole operated pump having a power piston reciprocated by alternating pressurized hydraulic fluid flow controlled at the surface by a hydraulic power control system which quickly reverses the flow direction.

Applicant's invention is distinguished from Schulte specifically in a number of ways. While Schulte teaches an apparatus having a power piston above the production piston, the present invention provides for a power piston below the production piston. Such configuration provides greater efficiency and allows the present system to be operated on much less energy.

Schulte teaches a power piston that runs along the well bore itself. However, the present invention provides for a power piston/production piston configuration whereby each piston is actuated within a removable tube housing located within the well bore. This feature provides for a straightforward maintenance or replacement scheme that is simply not available with devices known in the art.

Applicant's invention also provides a scheme whereby either the volume of the power piston or the volume of the production piston may be changed with respect to one another. As such, the power piston/production piston ratio may be manipulated to vary the power fluid/output fluid ratio for different situations. For example the size of the power piston may be increased with respect to the production piston. This scheme will allow the present system to be operated on an extremely small amount of power. In fact, such embodiments are thought to operate within the range of solar power sources this feature is not available with any known products. Alternatively, the size of the production piston could be increased with respect to the power piston. This scheme will allow the present system achieve rates of oil production not generally possible. For example, the present system will be able to produce 700-800 barrels of oil per day while accepted limitations fall around 400 barrels of oil a day. As mentioned, the components are housed in a removable tubing, as such, the power piston/production piston ratio may be changed in accordance with changing amounts and depths of available oil.

The present invention incorporates the use of coil tubing throughout the system. Coil tubing is known in the industry and is typically used to clean sand from well bores; however, no known products have been able to incorporate such tubing to transfer power fluid and provide housing for system components. In the past, fitting system components and power fluid tubing within coil tubing has proven to be too difficult. Applicant's invention, however, provides for the novel use of such tubing to transfer power fluid and house components. This feature makes Applicant's invention particularly useful in deviated oil wells when compared to presently available products.

The present invention is further distinguished over the prior art in general, and the Schulte patent in particular, by the use of water-based fluid rather than hydraulic fluid to actuate the downhole reciprocating pump unit. The substitution of water-based fluid for hydraulic fluid may appear to be a subtle distinction at first glance. Nevertheless, the use of water-based fluid in the present system has virtually eliminated the most common problems associated with presently proposed, but impractical hydraulic recovery systems, including: the compression of production fluid circulated though the system, inflexible fluid transfer lines, fluid friction during downhole and return flow cycles, and fluid viscosity.

In view of the limitations and hazards associated with traditional oil recovery systems, and the defects in presently proposed hydraulically operated oil recovery systems, a great need exists for a system that can operate efficiently and safely. Through use of coil tubing, water-based fluid rather than hydraulic fluid, and a unique combination of system components, Applicant's invention eliminates problems associated with known recovery systems and provides tremendous progress in view of those systems.

SUMMARY OF THE INVENTION

In view of the foregoing, it is an object of the present invention to provide an oil recovery system that eliminates conventional tubing wear and tear.

It is another object of the present invention to provide an oil recovery system that eliminates weak tubing link unreliability.

It is another object of the present invention to provide an oil recovery system that eliminates surface leaks.

It is another object of the present invention to provide an oil recovery system that eliminates pumping unit liability.

It is another object of the present invention to provide an oil recovery system that eliminates submersible pump inefficiencies.

It is another object of the present invention to provide an oil recovery system that may exceptionally useful in deviated oil wells.

It is another object of the present invention to present invention to provide an oil recovery system that produces and maintains relatively high volume lift in relatively low production wells.

It is another object of the present invention to provide an oil recovery system that may be used in environmentally sensitive locations.

It is another object of the present invention to provide an oil recovery system that may be safely used in urban environments.

It is another object of the present invention to provide an oil recovery system that may be used in corrosive environments.

It is another object of the present invention to provide an oil recovery system that may be used in remote locations.

It is another object of the present invention to provide an oil recovery system that contains a surface adjustable lift capacity.

It is another object of the present invention to provide an oil recovery system that may be used to recover particularly deep oil deposits.

It is another object of the present invention to provide an oil recovery system that can be powered by solar energy or other alternative power sources.

It is another object of the present invention to provide an oil recovery system that employs the use of coil production tubing.

It is another object of the present invention to provide an oil recovery system that maintains its power piston below its production piston.

It is another object of the present invention to provide an oil recovery system that employs the use of pressure controlled surface pumps.

It is another object of the present invention to provide an oil recovery system that requires an exceptionally low amount of service.

It is yet another object of the present invention to provide an oil recovery system that has an exceptionally long running life.

In satisfaction of these and related objects, and as will be discussed in the specification to follow, practice of the present invention involves a pressure-type pump surface unit. This surface unit is modified to read and react to pressure measurements during pump cycles so that when pressure builds past a certain point at the completion of a cycle, the unit “switches” to begin the next cycle. As mentioned, the surface unit of the present invention is of a pressure-type, and therefore is much smaller, quieter, and cleaner than standard oil well surface units.

The surface unit of the present invention is connected to a downhole apparatus by a pair of hydraulic power lines. The downhole unit of the present invention primarily consists of a power piston, a production piston, a connecting rod, and a series of valves and reservoirs. Operation of the system is initiated when power fluid is alternatingly pumped through each power line, thereby actuating a downhole power piston between a top position and a bottom position. Specifically, as fluid is pumped through the upstroke power line, the fluid volume of the reservoir below the power piston expands, thereby forcing the power piston upward. During the following downstroke, fluid is pumped through the downstroke power line, and the fluid volume of the reservoir above the power piston expands thereby forcing the power piston downward.

A connecting rod extends from the power piston to the production piston. In holding the power piston and production piston fixed with respect to one another, the connecting rod traverses both a hydraulic power fluid reservoir and an oil containing reservoir. Importantly, the connecting rod, in combination with the pump barrel, forms a fluid-tight seal between the power fluid reservoir and the oil reservoir. This feature allows the connecting rod to actuate between a top position and a down position while keeping the “dirty” oil environment separate from the “clean” power fluid environment.

The production piston rests along the top surface of the connecting rod and is actuated between a bottom position just above an oil inlet and a top position just below a one way-valve. These one-way valves are standard, “check” valves as known in the art. That is, each valve consists of a loosely seeded bearing that rests about a grooved slot. Each bearing is may become unseeded, thereby allowing fluid to flow in a given direction yet returns to a seeded position to prevent backflow of any fluid.

The production piston contains an interior shaft that runs through the interior of the shaft, and further contains a bottom one-way valve resting on the top surface of the piston, centered about the piston shaft. Oil is cycled from an inlet reservoir below the production piston, to a reservoir above the production piston and below a top valve, as the production piston is actuated from a top position to a bottom position. Specifically, during a downstroke, oil flows into the production shaft through a combination of holes placed within the top portion of the connecting rod. Oil is then sucked through the piston shaft and up through the bottom valve by the vacuum created between the bottom valve and top valve.

Oil is cycled from a reservoir between the bottom valve and the top valve to a reservoir above the top valve as the production piston is actuated from a bottom position to a top position. Specifically, the bottom valve remains in the seeded position as it rises, forcing oil through the top valve. As the bottom valve begins to lower, the top valve returns to the seeded position, preventing fluid from returning. This action also creates the vacuum that is responsible for sucking the oil through the production shaft and above the bottom valve. This process is repeated through a series of valves until the oil is cycled to the surface.

It is important to note that the general operation and the effectiveness of the present system does not depend on the exact arrangement of the component parts. Specifically, the power piston may be placed below or above the production fluid reservoirs. It is easily seen that production oil may still be pumped to the surface, with only minor changes needed in the arrangement of the system. In each arrangement, the efficiency of the present system is preserved.

As mentioned, Applicant's invention circulates a water-based fluid, rather than hydraulic fluid, throughout the system. This substitution promotes both the novel design and great efficiency of the present invention. More specifically, the use of water-based fluid provides for a much greater operating efficiency. That is, typical hydraulic fluid is compressible and therefore requires significantly more pump strokes to “pressure up” than a column of water-based fluid. As a result, the efficiency of hydraulic fluid decreases over any appreciable distance as its compression causes wasted pump strokes, which directly translates to lost power. Because the present system uses incompressible water-based fluid, problems associated with fluid compressibility have been eliminated. Specifically, power loss is avoided as there is no appreciable loss in efficiency due to the compression of the circulated production fluid.

Other useful embodiments of the invention are thought to utilized additives that my increase the viscosity of the water-based hydraulic fluid. Such may involve the use of “oils” to form emulsions. These embodiments are thought to be particularly useful in further reducing fluid friction and further improving operating efficiency.

However, the benefits associated with the present system do not end with use of water-based fluid. The novelty of the present invention further lies in the placement and action of the downhole pump. The downhole pump is placed below the production oil, as such, the surface unit is in a mechanically superior alignment. That is, the surface unit is responsible for actuating only the downhole pump, rather than cycling the entire production string through the production tube. This feature alone, and in conjunction with an efficient surface unit, provides for an extreme decrease in the energy used during production.

Devices of the past have not been successful in using coil tubing, as it has proven too difficult to incorporate such tubing within the production tube itself. However, Applicant has cleared that hurdle. The present system provides for the coiled, flexible tubing contained within the production tube all the while circulating water-based fluid from the surface to the downhole pump unit. This feature alone, and particularly in combination with coil production tubing, allows the present invention to be useful in deviated wells that otherwise be inaccessible.

BRIEF DESCRIPTION OF THE DRAWINGS

Applicant's invention may be further understood from a description of the accompanying drawings, wherein unless otherwise specified, like referenced numerals are intended to depict like components in the various views.

FIG. 1 is a cross sectional view of the improved hydraulic downhole oil recovery system of the present invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIG. 1, the improved hydraulic down-hole oil recovery system of the present invention is identified generally by the reference number 10. In the preferred embodiment, device 10 is primarily made of alloy metal and coil tubing.

Referring principally to FIG. 1, device 10 includes surface pump unit 12. Surface pump unit 12 sends a production fluid 14 through upstroke powerline 16 during one cycle and sends production fluid 14 through downstroke powerline 18 in a following downstroke cycle. Surface unit 12 reversibly engages with power lines 16 and 18 so as to form a fluid-tight seal, such seal is formed by standard tube fittings as known in the art. In the preferred embodiment, pump unit 12 is pressure pump, modified to contain a “switch off pressure sensor” 13 which reads the pressure at the surface pump on both the upstroke and the downstroke. At the point each stroke is carried out, pressure increases beyond a preset “switch off” point where sensor 13 sends a signal to pump 12 to begin the next stroke. Further, surface unit 12 transfers fluid 14 by alternating pressure on both power line 16 and power line 18, such pressure change may be carried out in a number of ways. Finally, in the preferred embodiment, production fluid 14 is water-based fluid. As previously discussed in the specification, the use of water-based fluid in conjunction with device 10 provides its user with a number of advantages.

Upstroke power line 16 and downstroke powerline 18 both extend from surface pump unit 12 and follow along the length of removable production tube 20. Production tube 20, in the preferred embodiment, reversibly slides along an outer shaft. In the preferred embodiment, upstroke powerline 16 and downstroke powerline 18 are comprised of coil production tubing. As previously discussed in the specification, powerline made of this material allow the present invention to be particularly useful in deviated oil wells.

Upstroke powerline 16 leads to upstroke reservoir 22 and is connected thereto by upstroke fitting 24. Downstroke powerline 18 leads to downstroke reservoir 26 and is connected thereto by downstroke fitting 28. Both fitting 24 and fitting 28 are standard tube fittings as known in the art.

As surface pump unit 12 sends production fluid 14 through upstroke power line 16, power fluid 14 fills upstroke reservoir 22 such that its fluid volume increases, thereby actuating power plunger 30 in an upward direction so that the fluid volume of downstroke reservoir 26 decreases. Likewise, as surface pump unit 12 sends production fluid 14 through downstroke power line 18, power fluid 14 fills downstroke reservoir 26 such that its fluid volume increases, thereby actuating power plunger 30 in a downward direction, so that the fluid volume of upstroke reservoir 22 decreases.

Again referring to FIG. 1, power plunger 30 is actuated between a top position and a bottom position where plunger bottom surface 31 reaches a position just above upstroke fixture 24 at completion of the downstroke in the bottom position; and where plunger top surface 33 reaches a position just below downstroke fixture 28 at completion of the upstroke in the top position. The pressure change in powerline 16 and 18, and resulting fluid volume change in reservoirs 22 and 26, respectively, is the mechanism responsible for actuating power plunger 30. In the preferred embodiment, power plunger 30 is a “spray metal” plunger, or made of some suitable alloy and is shaped so as to form a fluid-tight fit with removable production tube 20.

Again referring principally to FIG. 1, connecting rod 32 extends from plunger 30. Rod 32 is attached to power plunger 30 at rod bottom surface 34 and extends linearly therefrom in an upward direction. Rod 32 further contains rod top portion 36 and is of such length so that connection rod top portion 36 extends beyond pump barrel 38 during both the downstroke and the upstroke. Connecting rod top portion 36 further contains lateral inlet hole 42 and top inlet hole 44. Lateral inlet hole 42 and top inlet hole 44 allow production oil to flow through rod 32 to production piston shaft 46.

As seen in FIG. 1, rod 32 is actuated between a top position and a bottom position where top portion 36 rests just above pump barrel 38 in a bottom position at completion of a downstroke; and where portion 36 lifts production piston 46, and thereby traveling valve 50, to a position just below standing valve 54.

The combination of rod 32 and pump barrel 38 form a fluid-tight seal, as such, downstroke reservoir 26 remains completely sealed from pump inlet reservoir 40 during both the upstroke and downstroke. In the preferred embodiment, connecting rod 32 and pump barrel 38 are fitted so that a 1/1000th inch gap in found on either side of rod 32. This fit is thought to be most beneficial that it allows rod 32 to freely move between its top and bottom position while preventing production oil from flowing between rod 32 and pump barrel 38. Such a fluid tight seal formed by bottom surface 34 and barrel 38 is particularly beneficial in that it separates the clean environment of production fluid 14 from the dirty environment of the oil cycled by device 10. As previously discussed in the specification, this has not been possible with known hydraulically-driven systems.

Immediately above pump barrel 38 is pump inlet reservoir 40. Pump inlet reservoir 40 further contains inlet 41. During an upstroke, production fluid is drawn into device 10 through inlet 41 where it travels through and fills pump inlet reservoir 40. During a downstroke, oil flows through production shaft 48 and into traveling valve reservoir 53.

Production piston 46 is connected to and rests just above rod 32. Production piston 46 is of a generally solid cylinder-form and contains production piston shaft 48. In the preferred embodiment, shaft 48 extends along a central, interior portion of piston 46. Further, shaft 48 is centrally aligned with, and extends above rod 32. While the preferred embodiment incorporates a single shaft 48, other advantageous embodiments are envisioned where there are a plurality of aligned shafts, similar in form and function to shaft 48.

Production piston 46 is actuated between a top position and a bottom position where piston 46 bottom surface 47 reaches just above pump inlet 41 at completion of a downstroke in a bottom position; and piston top surface 49 reaches just below standing valve 52 at completion of an upstroke in a top position. As previously mentioned in the specification, the volume of both production piston 46 and power piston 30 may be changed with respect to one another. This change in ration between production piston 46 and power piston 30 has particular applicability in a low production energy context.

Traveling valve 50 is embedded within piston top surface 49. In the preferred embodiment, traveling valve 50 is of a standard type as known in the art. That is, a loosely seeded bearing 51 rests upon a grooved slot 52. During downstroke, bearing 51 becomes unseeded and allows oil to flow from pump inlet reservoir 40, through lateral hole 42 and top hole 44, through piston shaft 46, and into traveling valve reservoir 53. Oil easily flows into reservoir 53 as bearing 51 becomes unseeded and the oil is sucked into the reservoir 53 by the created vacuum between top surface 49 and standing valve 54. During upstroke, bearing 51 remains seeded so that valve 50 and production piston top surface 49 effectively form a wall, forcing oil through standing valve 54.

Standing valve 54 rests immediately above traveling valve reservoir 53. In the preferred embodiment, standing valve 54 is of a standard type as known in the art. That is, a loosely seeded bearing 55 rests upon a grooved slot 56. During upstroke, bearing 55 becomes unseeded and allows oil from reservoir 53, through valve 54, to standing valve reservoir 57. During downstroke, bearing 55 remains seeded and forms a seal so as to prevent oil from flowing back into reservoir.

Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions will become apparent to persons skilled in the art upon reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention. 

1. An improved hydraulic downhole oil recovery system, comprising: an above ground surface unit, further comprising a fluid transfer means for transferring a fluid through one or more fluid-transfer tubes, a pressure measuring means for measuring pressure on said fluid-transfer tubes a fluid-transfer tube receiving means; said fluid-transfer tubes, wherein said tubes mate with said above ground surface unit at a first end and mate with a submersible downhole unit at a second end; said submersible downhole unit, further comprising an inner removable shell, where said inner removable shell houses a plurality of fluid transfer tubes, a fluid-transfer tube receiving means, said fluid-transfer tube receiving means being reversibly mated with said fluid-transfer tube second end, and said fluid-transfer tube receiving means being located on either side of a power piston, said power piston, where said power piston is actuated between a first position and a second position by differential pressure exerted on either side of said power piston, a connecting rod extending between said power piston and a production piston, where said connecting rod holds said power piston and said production piston in a fixed position with respect to one another, a production piston, where said production piston is actuated between a first position and a second position by corresponding actuation of said power piston and connection rod, a plurality of valves allowing for one-way flow of a production fluid as said production fluid cycles through said inner removable housing.
 2. The improved hydraulic downhole oil recovery system of claim 1, where said inner removable shell further houses one or more apertures configured to allow production fluid to flow into said recovery system.
 3. The improved hydraulic downhole oil recovery system of claim 1, wherein said fluid-transfer tubes are comprised of coil tubing.
 4. The improved hydraulic downhole oil recovery system of claim 1, wherein said removable inner shell is comprised of coil tubing.
 5. The improved hydraulic downhole oil recovery system of claim 1, wherein said fluid is water-based fluid.
 6. A method of using an improved hydraulic downhole oil recovery system comprising the steps of selecting: an above ground surface unit, further comprising a fluid transfer means for transferring a fluid through one or more fluid-transfer tubes, a pressure measuring means for measuring pressure on said fluid-transfer tubes a fluid-transfer tube receiving means; said fluid-transfer tubes, wherein said tubes mate with said above ground surface unit at a first end and mate with a submersible downhole unit at a second end; said submersible downhole unit, further comprising an inner removable shell, where said inner removable shell houses a plurality of fluid transfer tubes, a fluid-transfer tube receiving means, said fluid-transfer tube receiving means being reversibly mated with said fluid-transfer tube second end, and said fluid-transfer tube receiving means being located on either side of a power piston, said power piston, where said power piston is actuated between a first position and a second position by differential pressure exerted on either side of said power piston, a connecting rod extending between said power piston and a production piston, where said connecting rod holds said power piston and said production piston in a fixed position with respect to one another, a production piston, where said production piston is actuated between a first position and a second position by corresponding actuation of said power piston and connection rod, a plurality of valves allowing for one-way flow of a production fluid as said production fluid cycles through said inner removable housing. 